Dyeing composition for keratinous fibers comprising a particular dicationic diazo dye

ABSTRACT

The invention concerns a dyeing composition for dyeing keratinous fibers, in particular human keratinous fibers and more particularly hair, comprising a dicationic diazo dye of formula W 1 —N═N—W 2 —N═N—W 3  as well as the dyeing method using same and the novel compounds of formula (I).

The invention relates to a novel dye composition for dyeing keratinfibers, in particular human keratin fibers and more particularly thehair, comprising dicationic diazo dye, and also to the process fordyeing keratin fibers using such a composition. The invention alsorelates to novel dicationic diazo dyes.

It is known practice to dye keratin fibers, and in particular humanhair, with dye compositions containing oxidation dye precursors, whichare generally known as oxidation bases, such as ortho- orpara-phenylenediamines, ortho- or para-aminophenols and heterocycliccompounds. These oxidation bases are colorless or weakly coloredcompounds, which, when combined with oxidizing products, give rise tocolored compounds by a process of oxidative condensation.

It is also known that the shades obtained with these oxidation bases maybe varied by combining them with couplers or coloration modifiers, thelatter agents being chosen especially from aromatic meta-diamines,meta-aminophenols, meta-diphenols and certain heterocyclic compoundssuch as indole compounds.

The variety of molecules used as oxidation bases and couplers allows awide range of colors to be obtained.

This process of oxidation dyeing consists in applying to the keratinfibers oxidation bases or a mixture of oxidation bases and of couplerswith an oxidizing agent, for example aqueous hydrogen peroxide solution,leaving the application on the fibers, and then rinsing the fibers. Thecolorations resulting therefrom are permanent, strong and fast withrespect to external agents, especially light, bad weather, washing,perspiration and rubbing. Generally applied at basic pH, dyeing andsimultaneous lightening of the fiber may be obtained, which is reflectedin practice by the possibility of obtaining a final coloration that islighter than the original color. In addition, lightening of the fibermay have the advantageous effect of producing a unified color in thecase of gray hair, and, in the case of naturally pigmented hair, ofbringing out the color, i.e. of making it more visible.

It is also known practice to dye keratin fibers by direct dyeing. Theprocess conventionally used in direct dyeing consists in applying to thekeratin fibers direct dyes, which are colored and coloring moleculesthat have affinity for the fibers, leaving the dyes on the fibers, andthen rinsing the fibers.

It is known practice, for example, to use direct dyes belonging to thenitrobenzene, anthraquinone, nitropyridine, azo, indoamine, azine ortriarylmethane class.

The colorations resulting therefrom are particularly chromaticcolorations, that are temporary or semi-permanent since the nature ofthe interactions binding the direct dyes to the keratin fiber, and theirdesorption from the surface and/or the core of the fiber are responsiblefor their poor dyeing power and their poor resistance to washing or toperspiration. These direct dyes are also generally light-sensitive dueto the poor resistance of the chromophore with respect to photochemicalattack, leading over time to fading of the coloration of the hair. Inaddition, their light sensitivity is dependent on their uniformdistribution or distribution as aggregates in the keratin fiber.

It is known practice to use direct dyes in combination with oxidizingagents. However, direct dyes are generally sensitive to the action ofoxidizing agents such as aqueous hydrogen peroxide solution, andreducing agents such as sodium bisulfite, which makes it generallydifficult to use them in compositions for lightening direct dyeing basedon aqueous hydrogen peroxide solution and based on a basifying agent orin oxidation dye compositions in combination with precursors such asoxidation bases or couplers.

For example, it has been proposed in patent applications FR-1 584 965and JP-062 711 435 to dye the hair with dye compositions based on nitrodirect dyes and/or dispersed azo dyes and on ammoniacal aqueous hydrogenperoxide solution, by applying to the hair a mixture of said dyes and ofsaid oxidizing agent, prepared just before use. However, the colorationsobtained are found to have insufficient resistance and disappear onshampooing, making the lightening of the hair fiber show through. Such acoloration becomes unattractive by changing over time.

It has also been proposed in patent applications JP-53 95693 and JP-55022 638 to dye the hair with compositions based on cationic direct dyesof oxazine type and on ammoniacal aqueous hydrogen peroxide solution, byapplying to the hair ammoniacal aqueous hydrogen peroxide solution in afirst step, followed by a composition based on the oxazine direct dye ina second step. This coloration is unsatisfactory because it requires aprocess that is made too slow by the leave-in times of the twosuccessive steps. If, besides that, an extemporaneous mixture of theoxazine direct dye with ammoniacal aqueous hydrogen peroxide solution isapplied to the hair, the hair fiber is not colored or at most, avirtually nonexistent coloration is obtained.

More recently, patent application FR 2 741 798 has disclosed dyecompositions containing direct dyes comprising at least one quaternizednitrogen atom of the azo or azomethine type, said compositions being forextemporaneous mixing at basic pH with an oxidizing composition. Thesecompositions make it possible to obtain uniform, resistant and brightcolorations with glints. However, they do not allow keratin fibers to bedyed as strongly as with oxidation dye compositions.

There is thus a real need to find chromatic direct dyes that allowkeratin fibers to be dyed as strongly as with oxidation dyes, which arejust as stable as oxidation dyes to light, which are also fast withrespect to bad weather, washing and perspiration, and which are alsostable enough in the presence of oxidizing and reducing agents to beable simultaneously to obtain lightening of the fiber either by usinglightening direct compositions containing them, or by using oxidationdye compositions containing them. There is also a real need to finddirect dyes that allow keratin fibers to be dyed in order to obtain avery wide range of colors, in particular very chromatic colors, notforgetting the “fundamental” shades, for instance, blacks and browns.

These aims are achieved with the present invention, one subject of whichis a composition for dyeing keratin fibers, and in particular humankeratin fibers and more particularly the hair, comprising at least onedicationic diazo dye of formula (I) below:W₁—N═N—W₂—N═N—W₃  Formula (I)in which

-   -   W₁ and W₃ independently of each other, a heteroaromatic radical        represented by the formulae (II) and (III) below:    -   W₂ represents a carbon-based, pyridine-based or pyridazine-based        aromatic group of formula (IV)        in which formulae (II), (III), (IV);    -   X₁ represents a nitrogen atom or a radical CR₅,    -   X₂ represents a nitrogen atom or a radical CR₆,    -   Z₁ represents an oxygen or sulfur atom or a radical NR₈,    -   Z₂ represents a nitrogen atom or a radical CR₉,    -   Z₃ represents a nitrogen atom or a radical CR₁₂,    -   Z₄ represents a nitrogen atom or a radical CR₁₃,    -   the bond a of the 5-membered cationic ring of formula (II) is        linked to the azo group of formula (I),    -   the bond b of the 6-membered cationic ring of formula (III) is        linked to the azo group of formula (I),    -   R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, represent, together        or independently of each other, a hydrogen atom, a linear or        branched C₁-C₁₆ hydrocarbon-based chain, saturated or        unsaturated, that can form one or more 3- to 6-membered        carbon-based rings, one or more carbon atoms of the carbon-based        chain of which may be replaced with an oxygen, nitrogen or        sulfur atom or with an SO₂ group, and the carbon atoms of which        may be substituted, independently of each other, with one or        more halogen atoms; R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃,        not comprising a peroxide bond or diazo or nitroso radicals,    -   R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form a        carbon-based aromatic ring, such as a phenyl,    -   X is an organic or mineral anion.

According to the invention, when it is indicated that one or more of thecarbon atoms of the hydrocarbon-based chain defined for the radicals L,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, R₁₃, may be replaced with anoxygen, nitrogen or sulfur atom or with an SO₂ group, and/or when thesehydrocarbon-based chains are unsaturated, this means that the followingconversions may be performed, for example:

In particular the term “branched hydrocarbon-based chain” means a chainthat can form one or more 3- to 6-membered carbon-based rings. The term“unsaturated hydrocarbon-based chain” means a chain that may compriseone or more double bonds and/or one or more triple bonds, thishydrocarbon-based chain possibly leading to aromatic groups.

X is an organic or mineral anion chosen, for example, from a halide suchas chloride, bromide, fluoride or iodide; a hydroxide; a sulfate; ahydrogen sulfate; a (C₁-C₆)alkyl sulfate, for example a methyl sulfateor an ethyl sulfate; an acetate; a tartrate; an oxalate; a(C₁-C₆)alkylsulfonate such as methylsulfonate; an arylsulfonate that isunsubstituted or substituted with a C₁-C₄ alkyl radical, for instance a4-tolylsulfonate.

R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃, preferably represent, independentlyof each other, a hydrogen atom; a linear or branched C₁-C₄ alkyl radicaloptionally substituted with one or more radicals chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; a phenyl radical optionally substitutedwith one or more radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals or a halogen atom such as chlorine, fluorine or bromine; acarboxyl radical; a sulfonylamino radical; a sulfonic radical; a C₁-C₂alkoxy radical; a C₂-C₄ (poly)hydroxyalkoxy radical; an amino radical; aC₁-C₂ (di)alkylamino radical; a C₂-C₄ (poly)hydroxylalkylamino radical.

More preferably, R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, R₁₃ represent a hydrogenatom, a C₁-C₄ alkyl radical optionally substituted with one or moreradicals chosen from hydroxyl, amino and C₁-C₂ (di)alkylamino radicals;a carboxyl radical; a C₁-C₂ alkoxy radical; an amino radical; a C₁-C₂(di)alkylamino radical; a C₂-C₄ (poly)hydroxyalkylamino radical.

According to one particularly preferred embodiment, R₃, R₄, R₅, R₆, R₁₀,R₁₁, R₁₂, R₁₃, represent a hydrogen atom, a methyl, phenyl or2-hydroxymethyl radical, a carboxyl, a methoxy, ethoxy or2-hydroxyethyloxy radical, or an amino, methylamino, dimethylamino or2-hydroxyethylamino radical.

R₇ and R₉ represent, independently of each other, a hydrogen atom; alinear or branched C₁-C₄ alkyl radical optionally substituted with oneor more radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; an optionally substituted phenyl radical; a carboxyl radical;a sulfonylamino radical.

Among these substituents, R₇ and R₉ preferably represent a hydrogenatom, a phenyl radical or a C₁-C₄ alkyl radical optionally substitutedwith one or more radicals chosen from hydroxyl, amino, C₁-C₂(di)alkylamino and carboxyl radicals.

According to a particularly preferred embodiment, R₇ and R₉ preferablyrepresent a hydrogen atom, a methyl, phenyl or 2-hydroxymethyl radicalor a carboxyl.

R₁, R₂ and R₈ represent a linear or branched C₁-C₈ alkyl radical,optionally substituted with one or more radicals chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; an optionally substituted phenylradical.

Among these substituents, R₁, R₂ and R₈ preferably represents a C₁-C₄alkyl radical optionally substituted with one or more radicals chosenfrom hydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl andsulfonic radicals.

According to one particularly preferred embodiment, R₁, R₂ and R₈preferably represent a methyl, ethyl, 2-hydroxyethyl, 1-carboxymethyl,2-carboxyethyl or 2-sulfonylethyl radical.

W₁ and W₃ preferably represent, independently of each other, animidazolium, triazolium, thiazolium or pyridinium cationic groupsubstituted by the preferred radicals R₁, R₇, R₁₀, R₁₁, R₁₂, R₁₃.

W₂ preferably represents a phenyl or pyridyl group substituted by thepreferred radicals R₃, R₄, R₅, R₆.

The concentration of dicationic diazo dye of formula (I) may range from0.001% to 5% by weight approximately, and preferably from about 0.05% to2% by weight, relative to the total weight of the dye composition.

Among the dicationic diazo dyes of formula (I) according to the presentinvention, mention may be made especially of the following compounds:

-   1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-yl-azo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(1,4-dimethyl(triazol-2-ium)-3-yl-azo)phenylazo]triazol-2-ium,-   1-methyl-2-[4-(1-methyl(pyridin-1-ium)-2-ylazo)-phenylazo]pyridin-1-ium,-   1-methyl-3-[4-(1-methyl(pyridin-1-ium)-3-ylazo)-phenylazo]pyridin-1-ium,-   1,3-dimethyl-2-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]triazol-2-ium,-   1,3-dimethyl-2-[4-(1,4-dimethyl(triazol-2-ium)-3-ylazo)phenylazo]imidazol-1-ium,-   1-methyl-2-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]pyridin-1-ium,-   1-methyl-3-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]pyridin-1-ium,-   1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-2-ylazo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(1-methyl(pyridin-1-ium)-2-ylazo)phenylazo]triazol-2-ium,-   1,3-dimethyl-2-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-2-ylazo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-2-ylazo)phenylazo]triazol-2-ium,-   1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-3-ylazo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(1-methyl(pyridin-1-ium)-3-ylazo)phenylazo]triazol-2-ium,-   1,3-dimethyl-2-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-3-ylazo)phenylazo]imidazol-1-ium,-   1,4-dimethyl-3-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-3-ylazo)phenylazo]triazol-2-ium,-   1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-ylazo)-3-methoxyphenylazo]imidazol-1-ium,-   1,3-dimethyl-2-[4-(1,4-dimethyl(triazol-2-ium)-3-ylazo)-3-methoxyphenylazo]imidazol-1-ium,-   1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-2-ylazo)-3-methoxyphenylazo]imidazol-1-ium.    Synthesis of the Compounds of the Invention

The methods for obtaining said compounds are based on reactions that arealready well known in the literature and disclosed, for example, in thefollowing documents: U.S. Pat. No. 3,291,788, GB-1 186 753, U.S. Pat.No. 3,271,383, EP-0 757 083 and U.S. Pat. No. 5,708,151.

A first synthetic principle consists in reacting a cationic heterocyclicazo compound 1 on one of the nitrogen atoms of the heterocycle in the4-methoxyphenylazo series with a 5- or 6-membered heterocyclic hydrazonederivative 2 or 2′ in a protic solvent at a temperature of between 25°C. and 150° C. Compounds 3 and 3′ may thus be obtained. In particular,the quaternary heterocycle may be an imidazolium, triazolium,thiazolium, thiadiazolium, oxazolium, pyridinium or pyridazinium.Compounds 3 or 3′ are reacted with an oxidizing agent, for instanceoxygen, persalts (for example persulfate), potassium ferrocyanide orsilver oxide, in a protic solvent at a temperature of between 0° C. and80° C., to give the dicationic diazo compounds 4 and 4′:

The same synthetic principle may be applied starting with cationic azocompounds 1″ to give the dicationic diazo compounds 4″.

A second synthetic principle consists in reacting a 5-memberedheterocycle such as an imidazole, thiazole, thiadiazole, triazole oroxazole with the diazonium salt derived from the azo compound 5 (or 9,respectively, obtained according to the standard literature methods: seethe references cited below) at a temperature of between −5° C. and 50°C., in a protic solvent and at acidic pH. The diazo compound 7 (or 10,respectively) is thus obtained and reacted with an alkyl halide or adialkyl sulfate in a solvent with a boiling point of between 60° C. and180° C., to give the dicationic diazo compound 4 (or 11, respectively):

The same synthetic principle may be applied to the condensation of thediazonium salt of the azo compound 9 with a 6-membered heterocycle togive, after alkylation, the dicationic diazo compound 4″:

In the formulae of the synthesis Scheme, Me denotes a CH₃ radical.

The dye composition in accordance with the invention may also containdirect dyes other than those of formula (I), these dyes possibly beingchosen especially from neutral, acidic or cationic nitrobenzene directdyes, neutral, acidic or cationic azo direct dyes, neutral, acidic orcationic quinone and in particular anthraquinone direct dyes, azinedirect dyes, methine direct dyes, triarylmethane direct dyes, indoaminedirect dyes and natural direct dyes.

Among the benzenic direct dyes that may be used according to theinvention, mention may be made, in a non-limiting manner, of thefollowing compounds:

-   1,4-diamino-2-nitrobenzene-   1-amino-2-nitro-4-(β-hydroxyethylamino)benzene-   1-amino-2-nitro-4-bis(β-hydroxyethyl)aminobenzene-   1,4-bis(β-hydroxyethylamino)-2-nitrobenzene-   1-β-hydroxyethylamino-2-nitro-4-bis-(β-hydroxyethylamino)benzene-   1-β-hydroxyethylamino-2-nitro-4-aminobenzene-   1-β-hydroxyethylamino-2-nitro-4-(ethyl)(β-hydroxyethyl)aminobenzene-   1-amino-3-methyl-4-β-hydroxyethylamino-6-nitrobenzene-   1-amino-2-nitro-4-β-hydroxyethylamino-5-chlorobenzene-   1,2-diamino-4-nitrobenzene-   1-amino-2-β-hydroxyethylamino-5-nitrobenzene-   1,2-bis(β-hydroxyethylamino)-4-nitrobenzene-   1-amino-2-[tris(hydroxymethyl)methylamino]-5-nitrobenzene-   1-hydroxy-2-amino-5-nitrobenzene-   1-hydroxy-2-amino-4-nitrobenzene-   1-hydroxy-3-nitro-4-aminobenzene-   1-hydroxy-2-amino-4,6-dinitrobenzene-   1-β-hydroxyethyloxy-2-β-hydroxyethylamino-5-nitrobenzene-   1-methoxy-2-β-hydroxyethylamino-5-nitrobenzene-   1-β-hydroxyethyloxy-3-methylamino-4-nitrobenzene-   1-β,γ-dihydroxypropyloxy-3-methylamino-4-nitrobenzene-   1-β-hydroxyethylamino-4-β,γ-dihydroxypropyloxy-2-nitrobenzene-   1-β,γ-dihydroxypropylamino-4-trifluoromethyl-2-nitrobenzene-   1-β-hydroxyethylamino-4-trifluoromethyl-2-nitrobenzene-   1-β-hydroxyethylamino-3-methyl-2-nitrobenzene-   1-β-aminoethylamino-5-methoxy-2-nitrobenzene-   1-hydroxy-2-chloro-6-ethylamino-4-nitrobenzene-   1-hydroxy-2-chloro-6-amino-4-nitrobenzene-   1-hydroxy-6-[bis(β-hydroxyethyl)amino]-3-nitrobenzene-   1-β-hydroxyethylamino-2-nitrobenzene-   1-hydroxy-4-β-hydroxyethylamino-3-nitrobenzene.

Among the azo direct dyes that may be used according to the invention,mention may be made of the cationic azo dyes described in patentapplications WO 95/15144, WO 95/01772 and EP 714 954, the content ofwhich forms an integral part of the invention.

Among these compounds, mention may be made most particularly of thefollowing dyes:

-   1,3-dimethyl-2-[[4-(dimethylamino)phenyl]azo]-1H-imidazolium    chloride,-   1,3-dimethyl-2-[(4-aminophenyl)azo]-1H-imidazolium chloride,-   1-methyl-4-[(methylphenylhydrazono)methyl]pyridinium methyl sulfate.

Among the azo direct dyes that may also be mentioned are the followingdyes described in the Colour Index International 3rd edition:

-   Disperse Red 17-   Acid Yellow 9-   Acid Black 1-   Basic Red 22-   Basic Red 76-   Basic Yellow 57-   Basic Brown 16-   Acid Yellow 36-   Acid Orange 7-   Acid Red 33-   Acid Red 35-   Basic Brown 17-   Acid Yellow 23-   Acid Orange 24-   Disperse Black 9.

Mention may also be made of1-(4′-aminodiphenylazo)-2-methyl-4-[bis(β-hydroxyethyl)amino]benzene and4-hydroxy-3-(2-methoxyphenylazo)-1-naphthalenesulfonic acid.

Among the quinone direct dyes that may be mentioned are the followingdyes:

-   Disperse Red 15-   Solvent Violet 13-   Acid Violet 43-   Disperse Violet 1-   Disperse Violet 4-   Disperse Blue 1-   Disperse Violet 8-   Disperse Blue 3-   Disperse Red 11-   Acid Blue 62-   Disperse Blue 7-   Basic Blue 22-   Disperse Violet 15-   Basic Blue 99    and also the following compounds:-   1-N-methylmorpholiniumpropylamino-4-hydroxyanthraquinone-   1-aminopropylamino-4-methylaminoanthraquinone-   1-aminopropylaminoanthraquinone-   5-β-hydroxyethyl-1,4-diaminoanthraquinone-   2-aminoethylaminoanthraquinone-   1,4-bis(β,γ-dihydroxypropylamino)anthraquinone

Among the azine dyes that may be mentioned are the following compounds:

-   Basic Blue 17-   Basic Red 2.

Among the triarylmethane dyes that may be used according to theinvention, mention may be made of the following compounds:

-   Basic Green 1-   Acid Blue 9-   Basic Violet 3-   Basic Violet 14-   Basic Blue 7-   Acid Violet 49-   Basic Blue 26-   Acid Blue 7

Among the indoamine dyes that may be used according to the invention,mention may be made of the following compounds:

-   2-β-hydroxyethylamino-5-[bis(β-4′-hydroxyethyl)-amino]anilino-1,4-benzoquinone;-   2-β-hydroxyethylamino-5-(2′-methoxy-4′-amino)anilino-1,4-benzoquinone;-   3-N(2′-chloro-4′-hydroxy)phenylacetylamino-6-methoxy-1,4-benzoquinoneimine;-   3-N(3′-chloro-4′-methylamino)phenylureido-6-methyl-1,4-benzoquinoneimine;-   3-[4′-N-(ethylcarbamylmethyl)amino]phenylureido-6-methyl-1,4-benzoquinoneimine.

Among the natural direct dyes that may be used according to theinvention, mention may be made of lawsone, juglone, alizarin, purpurin,carminic acid, kermesic acid, purpurogallin, protocatechaldehyde,indigo, isatin, curcumin, spinulosin and apigenidin. Extracts ordecoctions containing these natural dyes may also be used, andespecially henna-based poultices or extracts.

The additional direct dye(s) preferably represent(s) from 0.001% to. 20%by weight approximately, and even more preferably from 0.005% to 10% byweight approximately, relative to the total weight of the product.

The composition of the invention may also comprise an oxidizing agent.This oxidizing agent may be any oxidizing agent conventionally used forbleaching keratin fibers. The oxidizing agent is preferably chosen fromhydrogen peroxide, urea peroxide, alkali metal bromates, persalts suchas perborates and persulfates, peracids and enzymes, among which mentionmay be made of peroxidases, 2-electron oxidoreductases such as uricases,and 4-electron oxigenases such as laccases. The use of hydrogen peroxideis particularly preferred.

The composition according to the invention may also comprise anoxidation base. This oxidation base may be chosen from the oxidationbases conventionally used in oxidation dyeing, for examplepara-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols,ortho-aminophenols and heterocyclic bases.

Among the para-phenylenediamines that may be mentioned, for example, arepara-phenylenediamine, para-tolylenediamine,2-chloro-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine,2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine,2,5-dimethyl-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine,N,N-diethyl-para-phenylenediamine, N,N-dipropyl-para-phenylenediamine,4-amino-N,N-diethyl-3-methylaniline,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,4-N,N-bis(β-hydroxyethyl)amino-2-methylaniline,4-N,N-bis(β-hydroxyethyl)amino-2-chloroaniline,2-β-hydroxyethyl-para-phenylenediamine, 2-fluoro-para-phenylenediamine,2-isopropyl-para-phenylenediamine,N-(β-hydroxypropyl)-para-phenylenediamine,2-hydroxymethyl-para-phenylenediamine,N,N-dimethyl-3-methyl-para-phenylenediamine,N-ethyl-N-(β-hydroxyethyl)-para-phenylenediamine,N-(β,γ-dihydroxypropyl)-para-phenylenediamine,N-(4′-aminophenyl)-para-phenylenediamine,N-phenyl-para-phenylenediamine,2-β-hydroxyethyloxy-para-phenylenediamine,2-β-acetylaminoethyloxy-para-phenylenediamine,N-(β-methoxyethyl)-para-phenylenediamine, 4-amino-phenylpyrrolidine,2-thienyl-para-phenylenediamine, 2-β-hydroxyethylamino-5-aminotoluene,and the addition salts thereof with an acid.

Among the para-phenylenediamines mentioned above, para-phenylenediamine,para-tolylenediamine, 2-isopropyl-para-phenylenediamine,2-β-hydroxyethyl-para-phenylenediamine,2-β-hydroxyethyloxy-para-phenylenediamine,2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine,2,3-dimethyl-para-phenylenediamine,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,2-chloro-para-phenylenediamine and2-β-acetylaminoethyloxy-para-phenylenediamine, and the addition saltsthereof with an acid, are particularly preferred.

Among the bis(phenyl)alkylenediamines that may be mentioned, forexample, areN,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)-1,3-diaminopropanol,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)ethylenediamine,N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(4-methylaminophenyl)tetramethylenediamine,N,N′-bis(ethyl)-N,N′-bis(4′-amino-3′-methylphenyl)ethylenediamine and1,8-bis(2,5-diamino-phenoxy)-3,6-dioxaoctane, and the addition saltsthereof with an acid.

Among the para-aminophenols that may be mentioned, for example, arepara-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol,4-amino-3-hydroxymethylphenol, 4-amino-2-methylphenol,4-amino-2-hydroxymethylphenol, 4-amino-2-methoxymethylphenol,4-amino-2-aminomethylphenol,4-amino-2-(β-hydroxyethyl-aminomethyl)phenol and 4-amino-2-fluorophenol,and the addition salts thereof with an acid.

Among the ortho-aminophenols that may be mentioned, for example, are2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol and5-acetamido-2-aminophenol, and the addition salts thereof with an acid.

Among the heterocyclic bases that may be mentioned, for example, arepyridine derivatives, pyrimidine derivatives and pyrazole derivatives.

Among the pyridine derivatives that may be mentioned are the compoundsdescribed, for example, in patents GB 1 026 978 and GB 1 153 196, suchas 2,5-diaminopyridine, 2-(4-methoxyphenyl)amino-3-aminopyridine,2,3-diamino-6-methoxypyridine,2-(β-methoxyethyl)amino-3-amino-6-methoxypyridine and3,4-diaminopyridine, and the addition salts thereof with an acid.

Among the pyrimidine derivatives that can be mentioned are the compoundsdescribed, for example, in patents DE 2 359 399; JP 88-169 571; JP05-163 124; EP 0 770 375 or patent application WO 96/15765, such as2,4,5,6-tetraaminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine,2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidineand 2,5,6-triaminopyrimidine, and pyrazolopyrimidine derivatives such asthose mentioned in patent application FR-A-2 750 048 and among whichmention may be made of pyrazolo[1,5-a]pyrimidine-3,7-diamine;2,5-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;pyrazolo[1,5-a]pyrimidine-3,5-diamine;2,7-dimethylpyrazolo[1,5-a]pyrimidine-3,5-diamine;3-aminopyrazolo[1,5-a]pyrimidin-7-ol;3-aminopyrazolo-[1,5-a]pyrimidin-5-ol;2-(3-aminopyrazolo[1,5-a]pyrimidin-7-ylamino)ethanol,2-(7-aminopyrazolo[1,5-a]pyrimidin-3-ylamino)ethanol,2-[(3-aminopyrazolo[1,5-a]pyrimidin-7-yl)(2-hydroxyethyl)amino]ethanol,2-[(7-aminopyrazolo[1,5-a]pyrimidin-3-yl)(2-hydroxyethyl)amino]ethanol,5,6-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine,2,6-dimethylpyrazolo-[1,5-a]pyrimidine-3,7-diamine,2,5,N7,N7-tetramethyl-pyrazolo[1,5-a]pyrimidine-3,7-diamine and3-amino-5-methyl-7-imidazolylpropylaminopyrazolo[1,5-a]-pyrimidine, andthe addition salts thereof with an acid and the tautomeric formsthereof, when a tautomeric equilibrium exists.

Among the pyrazole derivatives that may be mentioned are the compoundsdescribed in patents DE 3 843 892 and DE 4 133 957 and patentapplications WO 94/08969, WO 94/08970, FR-A-2 733 749 and DE 195 43 988,such as 4,5-diamino-1-methylpyrazole,4,5-diamino-1-(β-hydroxyethyl)pyrazole, 3,4-diamino-pyrazole,4,5-diamino-1-(4′-chlorobenzyl)pyrazole,4,5-diamino-1,3-dimethylpyrazole, 4,5-diamino-3-methyl-1-phenylpyrazole,4,5-diamino-1-methyl-3-phenylpyrazole,4-amino-1,3-dimethyl-5-hydrazinopyrazole,1-benzyl-4,5-diamino-3-methylpyrazole,4,5-diamino-3-tert-butyl-1-methylpyrazole,4,5-diamino-1-tert-butyl-3-methylpyrazole,4,5-diamino-1-(β-hydroxyethyl)-3-methylpyrazole,4,5-diamino-1-ethyl-3-methylpyrazole,4,5-diamino-1-ethyl-3-(4′-methoxyphenyl)pyrazole,4,5-diamino-1-ethyl-3-hydroxymethylpyrazole,4,5-diamino-3-hydroxymethyl-1-methylpyrazole,4,5-diamino-3-hydroxymethyl-1-isopropylpyrazole,4,5-diamino-3-methyl-1-isopropylpyrazole,4-amino-5-(2′-aminoethyl)amino-1,3-dimethylpyrazole,3,4,5-triaminopyrazole, 1-methyl-3,4,5-triaminopyrazole,3,5-diamino-1-methyl-4-methylaminopyrazole and3,5-diamino-4-(β-hydroxyethyl)amino-1-methylpyrazole, and the additionsalts thereof with an acid.

The composition according to the invention may also contain one or morecouplers conventionally used for dyeing keratin fibers. Among thesecouplers, mention may be made especially of meta-phenylenediamines,meta-aminophenols, meta-diphenols, naphthalene-based couplers andheterocyclic couplers.

Examples that may be mentioned include 2-methyl-5-aminophenol,5-N-(β-hydroxyethyl)amino-2-methylphenol,6-chloro-2-methyl-5-aminophenol, 3-aminophenol, 1,3-dihydroxybenzene,1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene,2,4-diamino-1-(β-hydroxyethyloxy)benzene,2-amino-4-(β-hydroxyethylamino)-1-methoxybenzene, 1,3-diamino-benzene,1,3-bis(2,4-diaminophenoxy)propane, 3-ureido-aniline,3-ureido-1-dimethylaminobenzene, sesamol,1-β-hydroxyethylamino-3,4-methylenedioxybenzene, α-naphthol,2-methyl-1-naphthol, 6-hydroxyindole, 4-hydroxyindole,4-hydroxy-N-methylindole, 2-amino-3-hydroxypyridine,6-hydroxybenzomorpholine, 3,5-diamino-2,6-dimethoxypyridine,1-N-(β-hydroxyethyl)amino-3,4-methylenedioxybenzene and2,6-bis(β-hydroxyethylamino)toluene and the addition salts thereof withan acid.

In the composition of the present invention, the coupler(s) is(are)generally present in an amount ranging from 0.001% to 10% by weightapproximately, and more preferably from 0.005% to 6% by weight, relativeto the total weight of the dye composition. The oxidation base(s)is(are) present in an amount preferably ranging from

0.001% to 10% by weight approximately, and more preferably from 0.005%to 6% by weight, relative to the total weight of the dye composition.

In general, the addition salts with an acid that may be used in thecontext of the dye compositions of the invention for the oxidation basesand couplers are chosen especially from the hydrochlorides,hydrobromides, sulfates, citrates, succinates, tartrates, lactates,tosylates, benzenesulfonates, phosphates and acetates.

The medium that is suitable for dyeing, also known as the dye support,generally consists of water or a mixture of water and at least oneorganic solvent to dissolve the compounds which would not besufficiently soluble in water. As organic solvent, mention may be made,for example, of C₁-C₄ lower alkanols, such as ethanol and isopropanol;polyols and polyol ethers such as 2-butoxyethanol, propylene glycol,propylene glycol monomethyl ether, diethylene glycol monoethyl ether andmonomethyl ether, as well as aromatic alcohols such as benzyl alcohol orphenoxyethanol, and mixtures thereof.

The organic solvents may be present in proportions preferably of between1% and 40% by weight approximately relative to the total weight of thedye composition, and even more preferably between 5% and 30% by weightapproximately.

The dye composition in accordance with the invention can also containvarious adjuvants conventionally used in compositions for dyeing thehair, such as anionic, cationic, nonionic, amphoteric or zwitterionicsurfactants or mixtures thereof, anionic, cationic, nonionic, amphotericor zwitterionic polymers or mixtures thereof, inorganic or organicthickeners, and in particular anionic, cationic, nonionic or amphotericassociative polymeric thickeners, antioxidants, penetration agents,sequestering agents, fragrances, buffers, dispersing agents, packagingagents such as, for example, silicones, which may or may not be volatileor modified, film-forming agents, ceramides, preserving agents andopacifiers.

The above adjuvants are generally present in an amount for each of themof between 0.01% and 20% by weight relative to the weight of thecomposition.

Needless to say, a person skilled in the art will take care to selectthis or these optional additional compounds such that the advantageousproperties intrinsically associated with the oxidation dye compositionin accordance with the invention are not, or are not substantially,adversely affected by the addition(s) envisaged.

The pH of the dye composition in accordance with the invention isgenerally between about 3 and 12 and preferably between about 5 and 11.It may be adjusted to the desired value using acidifying or basifyingagents usually used in the dyeing of keratin fibers, or alternativelyusing standard buffer systems.

Among the acidifying agents which may be mentioned, for example, areinorganic or organic acids such as hydrochloric acid, orthophosphoricacid, sulfuric acid, carboxylic acids such as acetic acid, tartaricacid, citric acid and lactic acid, and sulfonic acids.

Among the basifying agents which may be mentioned, for example, areaqueous ammonia, alkaline carbonates, alkanolamines such as mono-, di-and triethanolamine and derivatives thereof, sodium hydroxide, potassiumhydroxide and the compounds of formula (III) below:

in which W is a propylene residue which is unsubstituted or substitutedwith a hydroxyl group or a C₁-C₄ alkyl radical; R₆, R₇, R₈ and R₉, whichmay be identical or different, represent a hydrogen atom, a C₁-C₄ alkylradical or a C₁-C₄ hydroxyalkyl radical.

The dye composition according to the invention may be in various forms,such as in the form of liquids, creams or gels, or in any other formthat is suitable for dyeing keratin fibers, and especially human hair.

A subject of the invention is also a process of direct dyeing, whichcomprises the application of a dye composition containing a dye offormula (I) as defined above to keratin fibers. After a leave-in time,the keratin fibers are rinsed, revealing colored fibers.

The dye composition containing the cationic azo dye of formula (I) maybe applied to the fibers in the presence of an oxidizing agent, whichcauses bleaching of the fiber (lightening direct dyeing). This oxidizingagent may be added to the composition containing the dye of formula (I)at the time of use or directly onto the keratin fiber.

A subject of the invention is also a process of oxidation dyeing, whichcomprises the application to the fibers of a dye composition comprisinga dye of formula (I), at least one oxidation base and optionally atleast one coupler, in the presence of an oxidizing agent.

The oxidation base, the coupler and the oxidizing agent are as definedabove.

The color may be revealed at acidic, neutral or alkaline pH and theoxidizing agent may be added to the composition of the invention just atthe time of use, or it may be introduced using an oxidizing compositioncontaining it, applied to the fibers simultaneously with or sequentiallyto the dye composition.

In the case of oxidation dyeing or lightening direct dyeing, the dyecomposition is mixed, preferably at the time of use, with a compositioncontaining, in a medium that is suitable for dyeing, at least oneoxidizing agent, this oxidizing agent being present in an amount that issufficient to develop a coloration. The mixture obtained is then appliedto the keratin fibers. After a leave-in time of 3 to 50 minutesapproximately and preferably 5 to 30 minutes approximately, the keratinfibers are rinsed, washed with shampoo, rinsed again and then dried.

The oxidizing composition may also contain various adjuvantsconventionally used in compositions for dyeing the hair, and as definedabove.

The pH of the oxidizing composition containing the oxidizing agent issuch that, after mixing with the dye composition, the pH of theresulting composition applied to the keratin fibers preferably rangesfrom 3 to 12 approximately, and even more preferably between 5 and 11.It may be adjusted to the desired value by means of acidifying orbasifying agents usually used in the dyeing of keratin fibers, and asdefined above.

The composition that is finally applied to the keratin fibers may be invarious forms, such as in the form of liquids, creams or gels or in anyother form that is suitable for dyeing keratin fibers, and especiallyhuman hair.

Another subject of the invention is a multi-compartment device or dyeing“kit”, in which a first compartment contains the dye composition of theinvention and a second compartment contains the oxidizing composition.This device may be equipped with a means for applying the desiredmixture to the hair, such as the devices described in patent FR-2 586913 in the name of the Applicant.

Finally, a subject of the invention is also the dicationic diazo dyes offormula (I) as defined above.

The example that follows serves to illustrate the invention without,however, being limiting in nature.

EXAMPLE

Synthesis of1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-ylazo)phenylazo]imidazol-1-iumdichlorate:

An ethanolic solution of1,3-dimethyl(1,3-dihydroimidazol-2-ylidene)hydrazone hydrochloride (1.2mol), neutralized beforehand with one equivalent of ethanolic sodiumhydroxide at room temperature, is added with stirring to an ethanolicsolution of 1,3-dimethyl-2-[4-methoxyphenylazo]imidazol-1-ium chlorate(1 mmol) (obtained according to the protocol described above). Thereaction medium is gradually brought to reflux and is then cooled to 25°C. after the reagents have disappeared. The reaction medium is stirredunder air overnight after addition of one equivalent of perchloric acid,and is then cooled to 0° C. and the precipitate is drained by suction,washed with ethyl acetate and dried to constant weight. 0.1 mmol of1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-ylazo)phenylazo]imidazol-1-iumdichlorate is thus obtained, the λ_(max) of which is 585 nm inmethanolic solution.

The dye obtained dyed hair in a violet shade.

1. A composition for dyeing keratin fibers, comprising at least onedicationic diazo dye of formula (I) below:W₁—N═N—W₂—N═N—W₃ wherein W₁ and W₃, which may be identical or different,are chosen from heteroaromatic groups chosen from formulae (II) and(III) below:

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV)

wherein, in formulae (II), (III), and (IV): X₁ is chosen from nitrogenand CR₅, X₂ is chosen from nitrogen and CR₆, Z₁ is chosen from oxygen,sulfur and NR₈, Z₂ is chosen from nitrogen and CR₉, Z₃ is chosen fromnitrogen and CR₁₂, Z₄ is chosen from nitrogen and CR₁₃, bond a of the5-membered cationic ring of formula (II) may be linked to the azo groupof formula (I), bond b of the 6-membered cationic ring of formula (III)may be linked to the azo group of formula (I), R₃, R₄, R₅, R₆, R₇, R₉,R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, are chosenfrom hydrogen and frorp linear and branched, saturated and unsaturated,C₁-C₁₆ hydrocarbon-based chains, wherein the chains can form at leastone carbon-based ring comprising from 3 to 6 carbons, wherein at leastone carbon atom of the carbon-based chain may be replaced with an entitychosen from oxygen, nitrogen and sulfur atoms and SO₂ groups, andwherein the at least one carbon atom may be substituted with at leastone halogen atom; wherein none of R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂,and R₁₃, comprises a peroxide bond, a diazo radical or a nitrosoradical, R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form carbon-basedaromatic rings, and X is chosen from organic and mineral anions.
 2. Thecomposition according to claim 1, wherein the keratin fibers are humankeratin fibers.
 3. The composition according to claim 2, wherein thehuman keratin fibers are hair.
 4. The composition according to claim 1,wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, and R₁₃, which may be identicalor different, are chosen from hydrogen; linear and branched C₁-C₄ alkylradicals, optionally substituted with at least one substituent chosenfrom hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxylalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl, and sulfonic radicals; phenyl radicalsoptionally substituted with at least one substituent chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals and halogen atoms;carboxyl radicals; sulfonylamino radicals; sulfonic radicals; C₁-C₂alkoxy radicals; C₂-C₄ (poly)hydroxyalkoxy radicals; amino radicals;C₁-C₂ (di)alkylamino radicals; and C₂-C₄ (poly)hydroxyalkylaminoradicals.
 5. The composition according to claim 4, wherein R₃, R₄, R₅,R₆, R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, arechosen from hydrogen; C₁-C₄ alkyl radicals optionally substituted withat least one substituent chosen from hydroxyl, amino and C₁-C₂(di)alkylamino radicals; carboxyl radicals; C₁-C₂ alkoxy radicals; aminoradicals; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 6. The composition according to claim5, wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂, and R₁₃, which may beidentical or different, are chosen from hydrogen, and from methyl,phenyl, 2-hydroxymethyl, carboxyl, methoxy, ethoxy, 2-hydroxyethyloxy,amino, methylamino, dimethylamino and 2-hydrooyethyl amino radicals. 7.The composition according to claim 1, wherein R₇ and R₉, which may beidentical or different, are chosen from hydrogen; linear and branchedC₁-C₄ alkyl radicals optionally substituted with at least onesubstituent chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; optiopally substituted phenyl radicals; carboxyl radicals; andsulfonylamino radicals.
 8. The composition according to claim 7, whereinR₇ and R₉, which may be identical or different, are chosen fromhydrogen, phenyl radicais, and C₁-C₄ alkyl radicals optionallysubstituted with at least one substituent chosen from hydroxyl, amino,C₁-C₂ (di)alkylamino and carboxyl radicals.
 9. The composition accordingto claim 8, wherein R₇ and R₉, which may be identical or different, arechosen from hydrogen and from methyl, phenyl, 2-hydroxymethyl, andcarboxyl radicals.
 10. The composition according to claim 1, wherein R₁,R₂ and R₈, which may be identical or different, are chosen from linearand branched C₁-C₈ alkyl radicals, optionally substituted with at leastone substituent chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonicradicals; and optionally substituted phenyl radicals.
 11. Thecomposition according to claim 10, wherein R₁, R₂ and R₈, which may beidentical or different, are chosen from C₁-C₄ alkyl radicals optionallysubstituted with at least one substituent chosen from hydroxyl, C₁-C₂alkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals. 12.The composition according to claim 11, wherein R₁, R₂ and R₈, which canbe identical or different, are chosen from methyl, ethyl,2-hydroxyethyl, 1-carboxymethyl, 2-carboxyethyl and 2-sulfonylethylradicals.
 13. The composition according to claim 1, wherein W₁ and W₃,which may be identical of different, are chosen from imidazolium,triazolium, thiazolium and pyridinium cationic groups substituted by atleast one substituent chosen from R₁, R₇, R₁₀, R₁₁, R₁₂, and R₁₃. 14.The composition according to claim 1, wherein W₂ is chosen from phenyland pyridyl groups substituted by at least one substituent chosen fromR₃, R₄, R₅, and R₆.
 15. The composition according to claim 1, whereinthe at least one diazo dicationic dye of formula (I) is chosen from:1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(1,4-dimethyl(triazol-2-ium)-3-ylazo)phenylazo]triazol-2-ium,1-methyl-2-[4-(1-methyl(pyrid in-1-ium)-2-ylazo)phenylazo]pyridin-1-ium,1-methyl-3-[4-(1-methyl(pyridin-1-ium)-3-ylazo)phenylazo]pyridin-1-ium,1,3-dimethyl-2-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]triazol-2-ium,1,3-dimethyl-2-[4-(1,4-dimethyl(triazol-2-ium)-3-ylazo)phenylazo]imidazol-1-ium,1-methyl-2-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]pyridin-1-ium,1-methyl-3-[4-(3-methyl(thiazol-3-ium)-2-ylazo)phenylazo]pyridin-1-ium,1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-2-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(1-methyl(pyridin-1-ium)-2-ylazo)phenylazo]triazol-2-ium,1,3-dimethyl-2-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-2-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-2-ylazo)phenylazo]triazol-2-ium,1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-3-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(1-methyl(pyridin-1-ium)-3-ylazo)phenylazo]triazol-2-ium,1,3-dimethyl-2-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-3-ylazo)phenylazo]imidazol-1-ium,1,4-dimethyl-3-[4-(1-(2-hydroxyethyl)(pyridin-1-ium)-3-ylazo)phenylazo]triazol-2-ium,1,3-dimethyl-2-[4-(1,3-dimethyl(imidazol-1-ium)-2-ylazo)-3-methoxyphenylazo]imidazol-1-ium,1,3-dimethyl-2-[4-(1,4-dimethyl(triazol-2-ium)-3-ylazo)-3-methoxyphenylazo]imidazol-1-ium,and1,3-dimethyl-2-[4-(1-methyl(pyridin-1-ium)-2-ylazo)-3-methoxyphenylazo]-midazol-1-ium.16. The composition according to claim 1, wherein the at least onedicationic diazo dye of formula (I) is present in an amount ranging from0.001% to 5% by weight, relative to the total weight of the composition.17. The composition according to claim 16, wherein the at least onedicationic diazo dye of formula (I) is present in an amount ranging from0.05% to 2% by weight, relative to the total weight of the composition.18. The composition according to claim 1, wherein the compositionfurther comprises at least one oxidation base.
 19. The compositionaccording to claim 18, wherein the at least one oxidation base is chosenfrom para-phenylenediamines, bis(phenyl)alkylenediamines,para-aminophenols, ortho-aminophenols and heterocyclic bases, and theacid addition salts thereof.
 20. The composition according to claim 18,wherein the at least one oxidation base is present in an amount rangingfrom 0.001% to 10% by weight, relative to the total weight of thecomposition.
 21. The composition according to claim 20, wherein the atleast one oxidation base is present in an amount ranging from 0.005% to6% by weight, relative to the total weight of the composition.
 22. Thecomposition according to claim 1, wherein the composition furthercomprises at least one coupler.
 23. The composition according to claim22, wherein the at least one coupler is chosen frommeta-phenylenediamines, meta-aminophenols, meta-diphenols,naphthalene-based couplers and heterocyclic couplers, and the acidaddition salts thereof.
 24. The composition according to claim 1,wherein the composition further comprises at least one direct dye otherthan those of formula (I), chosen from neutral, acidic and cationicnitrobenzene direct dyes, neutral, acidic and cationic azo direct dyes,neutral, acidic and cationic quinones.
 25. The composition according toclaim 24, wherein the at least one direct dye is chosen fromanthraquinone, azine, methine, triarylmethane, indoamine and naturaldirect dyes.
 26. The composition according to claim 1, wherein thecomposition further comprises at least one oxidizing agent.
 27. Thecomposition according to claim 26, wherein the at least one oxidizingagent is hydrogen peroxide.
 28. A process for dyeing keratin fiberscomprising applying to said fibers a dye composition comprising at leastone dicationic diazo dye of formula (I) below:W₁—N═N—W₂—N═N—W₃ wherein W₁ and W₃, which may be identical or different,are chosen from heteroaromatic groups chosen from formulae (II) and(III) below:

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV)

wherein, in formulae (II), (III), and (IV): X₁ is chosen from nitrogenand CR₅, X₂ is chosen from nitrogen and CR₆, Z₁ is chosen from oxygen,sulfur and NR₈, Z₂ is chosen from nitrogen and CR₉, Z₃ is chosen fromnitrogen and CR₁₂, Z₄ is chosen from nitrogen and CR₁₃, bond a of the5-membered cationic ring of formula (II) may be linked to the azo groupof formula (I), bond b of the 6-membered cationic ring of formula (III)may be linked to the azo group of formula (I), R₃, R₄, R₅, R₆, R₇, R₉,R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, are chosenfrom hydrogen, linear and branched, saturated and unsaturated, C₁-C₁₆hydrocarbon-based chains, wherein the chains can form at least onecarbon-based ring comprising from 3 to 6 carbons, wherein at least onecarbon of the carbon-based chain may be replaced with at least oneentity chosen from oxygen, nitrogen and sulfur atoms and SO₂ groups, andwherein the at least one carbon atom may be substituted with at leastone halogen atom; wherein none of R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂,and R₁₃, comprises a peroxide bond, a diazo radical, or a nitrosoradical, R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form carbon-basedaromatic rings, and X is chosen from organic and mineral anions.
 29. Theprocess according to claim 28, wherein the keratin fibers are humankeratin fibers.
 30. The process according to claim 29, wherein the humankeratin fibers are hair.
 31. The process according to claim 28, whereinthe dye composition further comprises at least one oxidizing agent. 32.The process according to claim 31, wherein the at least one oxidizingagent is mixed with the dye composition at the time of application. 33.The process according to claim 31, wherein the at least one oxidizingagent is applied to the fibers in the form of an oxidizing compositionsimultaneously with or sequentially to the application of the dyecomposition.
 34. A process for the oxidation dyeing of keratin fiberscomprising applying to said fibers, in the presence of at least oneoxidizing agent, a dye composition comprising at least one dicationicdiazo dye of formula (I) below, at least one oxidation base, andoptionally at least one coupler:W₁—N═N—W₂—N═N—W₃ wherein W₁ and W₃, which may be identical or different,are chosen from heteroaromatic groups chosen from formulae (II) and(III) below:

W₂ is chosen from carbon-based, pyridine-based arid pyridazine-basedaromatic groups of formula (IV)

wherein, in formulae (II), (III), and (IV): X₁ is chosen from nitrogenand CR₅, X₂ is chosen from nitrogen and CR₆, Z₁ is chosen from oxygen,sulfur and NR₈, Z₂ is chosen from nitrogen and CR₉, Z₃ is chosen fromnitrogen and CR₁₂, Z₄ is chosen from nitrogen and CR₁₃, bond a of the5-membered cationic ring of formula (II) may be linked to the azo groupof formula (I), bond b of the 6-membered cationic ring of formula (III)may be linked to the azo group of formula (I), R₃, R₄, R₅, R₆, R₇, R₉,R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, are chosenfrom hydrogen, linear and branched, saturated and unsaturated, C₁-C₁₆hydrocarbon-based chains, wherein the chains can form at least onecarbon-based ring comprising from 3 to 6 carbons, wherein at least onecarbon of the carbon-based chain may be replaced with an entity chosenfrom oxygen, nitrogen and sulfur atoms and SO₂ groups, and wherein theat least one carbon atom may be substituted with at least one halogenatom; wherein none of R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, and R₁₃,comprises a peroxide bond, a diazo radical or a nitroso radical, R₇ withR₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form carbon-based aromatic rings,and X is chosen from organic and mineral anions.
 35. The processaccording to claim 34, wherein the keratin fibers are human keratinfibers.
 36. The process according to claim 35, wherein the human keratinfibers are hair.
 37. The process according to claim 34, wherein the atleast one oxidizing agent is mixed with the dye composition at the timeof application.
 38. The process according to claim 37, wherein the atleast one oxidizing agent is applied to the fibers in the form of anoxidizing composition simultaneously with or sequentially to theapplication of the dye composition.
 39. A multi-compartment dyeingdevice, comprising at least two compartments, wherein the firstcompartment comprises at least one dicationic diazo dye of formula (I)below:W₁—N═N—W₂—N═N—W₃ wherein W₁ and W₃, which may be identical or different,are chosen from heteroaromatic groups chosen from formulae (II) and(III) below:

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV)

wherein, in formulae (II), (III), and (IV): X₁ is chosen from nitrogenand CR₅, X₂ is chosen from nitrogen and CR₆, Z₁ is chosen from oxygen,sulfur and NR₈, Z₂ is chosen from nitrogen and CR₉, Z₃ is chosen fromnitrogen and CR₁₂, Z₄ is chosen from nitrogen and CR₁₃, bond a of the5-membered cationic ring of formula (II) may be linked to the azo groupof formula (I), bond b of the 6-membered cationic ring of formula (III)may be linked to the azo group of formula (I), R₃, R₄, R₅, R₆, R₇, R₉,R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, are chosenfrom hydrogen, linear and branched, saturated and unsaturated, C₁-C₁₆hydrocarbon-based chains, wherein the chains can form at least onecarbon-based ring comprising from 3 to 6 carbons, wherein at least onecarbon of the carbon-based chain may be replaced with an entity chosenfrom oxygen, nitrogen and sulfur atoms and SO₂ groups, and wherein theat least one carbon atom may be substituted with at least one halogenatom; and wherein none of R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, and R₁₃comprises a peroxide bond, a diazo radical, or a nitroso radical, R₇with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form carbon-based aromaticrings, and X is chosen from organic and mineral anions, and the secondcompartment comprises at least one oxidizing composition.
 40. Adicationic diazo compound of formula (I):W₁—N═N—W₂—N═N—W₃ wherein W₁ and W₃, which may be identical or different,are chosen from heteroaromatic groups chosen from formulae (II) and(III) below:

W₂ is chosen from carbon-based, pyridine-based and pyridazine-basedaromatic groups of formula (IV)

wherein, in formulae (II), (III), and (IV): X₁ is chosen from nitrogenand CR₅, X₂ is chosen from nitrogen and CR₆, Z₁ is chosen from oxygen,sulfur and NR₈, Z₂ is chosen from nitrogen and CR₉, Z₃ is chosen fromnitrogen and CR₁₂, Z₄ is chosen from nitrogen and CR₁₃, bond a of the5-membered cationic ring of formula (II) may be linked to the azo groupof formula (I), bond b of the 6-membered cationic ring of formula (III)may be linked to the azo group of formula (I), R₃, R₄, R₆, R₆, R₇, R₉,R₁₀, R₁₁, R₁₂, and R₁₃, which may be identical or different, are chosenfrom hydrogen, linear and branched, saturated and unsaturated, C₁-C₁₆hydrocarbon-based chains, wherein the chains can form at least onecarbon-based ring comprising from 3 to 6 carbons, wherein at least onecarbon of the carbon-based chain may be replaced with an entity chosenfrom oxygen, nitrogen and sulfur atoms and SO₂ groups, and wherein theat least one carbon atom may be substituted with at least one halogenatom; and wherein none of R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂, and R₁₃comprises a peroxide bond, a diazo radical, or a nitroso radical, R₇with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ may form carbon-based aromaticrings, and X is chosen from organic and mineral anions.